(1) Field of the Invention
The present invention relates to optical articles made of an amorphous thermoplastic polyester resin. More particularly, the present invention relates to optical articles such as optical disks and optical lenses which are made of an amorphous polyester resin having aromatic rings in the main chain and the side chain of the recurring nits. The optical articles have a good heat resistance, resistance to absorption of moisture and optical characteristics.
(2) Description of the Related Art
Plastics have an excellent processability and productivity as industrial materials, and have a light weight, and these excellent characteristics have increased the demands for the utilization of plastics. Poly(methyl methacrylate) and polycarbonates are mainly used as the plastics for optical materials at present.
Poly(methyl methacrylate) has excellent optical characteristics but an unsatisfactory heat resistance and resistance to absorption of moisture. Accordingly, for example, deformation of an optical disk or a deformation of grooves often occurs during use. In contrast, a polycarbonate has an excellent heat resistance but a poor melt flowability and moldability, and a problem arise of a large birefringence due to molding distortion. A resin for an optical material must have a good heat resistance, an excellent transparency, and a small birefringence, but a resin for an optical material which is capable of satisfying these requirements has not been developed.